This invention relates to structure of a hose joint, for connecting a hose to a high temperature apparatus such as piping, pump and valve, with an object of protecting the former from heat damage caused by the latter.
It is usually practiced for taking out gaseous pressure with a hose from a high temperature apparatus to employ a metal-made hose joint in such a way as to be threadedly connected on one end thereof to the high temperature apparatus and to be fitted, on the other end thereof, on by a hose.
As the hose in such a case an organic elastic material such as synthetic rubber is generally used as its material, when a hose of synthetic rubber is subjected to, via the hose joint, high temperature beyond its resistible limit caused by the apparatus which is possibly of high temperature, the very hose is liable to be deteriorated by the heat. Particularly when the high temperature apparatus happens to be an intake manifold of an internal combustion engine, a hose for taking out negative pressure of the intake manifold may possibly be deteriorated to become fragile. It can cause a brake booster or an ignition timing regulating device which utilizes the negative pressure to be inoperative, leading to a grave accident.
For avoiding such a disadvantage elongation of the hose joint for isolating the hose from the intake manifold has been proposed and practiced, which is however not so practicable, because the hose joint is likely to be weakened by engine vibration and to additionally narrow the confined engine room all the more. Another idea of employing a hose of highly resistible to a high temperature inevitably brings about a cost rising therefor.